1. Technical Field
The embodiments described herein relate to a semiconductor integrated circuit, and more particularly, to a semiconductor memory apparatus.
2. Related Art
In general, a semiconductor memory apparatus uses an internal voltage that is internally produced, as well as an external voltage supplied from an external circuit. There are many advantages in using the internal voltage including achieving a stable operation by obtaining a stable voltage regardless of the external voltage and reducing current consumption.
FIG. 1 is a block diagram of a conventional semiconductor memory apparatus. In FIG. 1, a semiconductor memory apparatus 1 includes a power-up signal generator 10 and an internal voltage generator 20. The power-up signal generator 10 produces a power-up signal ‘pwrup’ that is enabled at a specific voltage level of the external voltage when the external voltage is supplied to the semiconductor memory apparatus 1.
The internal voltage generator 20 is initialized by the power-up signal ‘pwrup’ and produces an internal voltage ‘V_in’ of a target level when the power-up signal ‘pwrup’ is enabled. Here, the internal voltage generator 20 cannot produce the internal voltage ‘V_in’ of the target level if it is not sufficiently initialized. For example, when the internal voltage generator 20 is not sufficiently initialized and the power-up signal ‘pwrup’ is enabled, the internal voltage generator 20 cannot produce the internal voltage ‘V_in’, which has the target level. This problem is frequently caused when the enable timing of the power-up signal ‘pwrup’ is varied according to the variation of process, voltage, and temperature (PVT) variable in the power-up signal generator 10.